Such disorders are generally provoked by the presence, on the inner walls of the canal, of deposits causing strictures or stenoses in said canal.
The treatment of such disorders generally calls for the use of a dilatation catheter for restoring the normal flowing section of the canal at the level of the stenosis by compression with the aid of a balloon.
A guide, nomally produced in the form of a wire is used for helping the catheter to reach the stenosis.
The guide-wire is generally longer than the catheter, say about 20 to 50 cm, in order to urge the catheter forward into the body canal, by sliding it along the wire.
During an operation using the dilatation catheter, it may be necessary, in some cases to change the catheter while leaving the guide-wire in position, for example in case of difficult progression inside the coronaries.
It is known for example from U.S. Pat. No. 4,748,982, incorporated herein by way of reference, to use a so-called "rapid-exchange catheter" of which the distal part comprises two juxtaposed, non-communicating inner ducts, of which one, which is meant for the guide-wire to pass through, issues outside the catheter.
Inasmuch as the guide-wire passes through said catheter only over a small portion of its length, say 20 to 25 cm for a catheter reaching a total length of about 130 cm, said portion being smaller than the length of the wire extending out of the body, i.e. between 35 and 55 cm, it is possible to remove it while keeping said wire in position, and by sliding it along the guide-wire. The initial catheter can thus be replaced with another, without the need to use a specific exchange wire or an extension.
For correctly positioning the balloon at the level of the stenosis, it is necessary to bring the distal end of the catheter to beyond said stenosis.
Understandably, for the catheter to pass through the stenosis, it is generally necessary to apply a thrusting pressure on the latter.
Said thrusting pressure is exerted by the practitioner at the level of the proximal end of the catheter.
Transmission of said thrusting pressure to the distal end of the catheter raises a problem which, heretofore, has not been solved satisfactorily.